In circular knitting machines of the type used for making deep pile fabric, a plurality of stationary fiber feeding stations are located at circumferentially spaced positions about a rotating needle cylinder which carries vertically reciprocable knitting needles in slots or grooves in its periphery. Each feeding station has a doffer roll adapted to supply fiber to the needles. A stationary latch guard is employed in the vicinity of the doffer roll of each individual such feeding station to provide assurance that the latch of each needle is maintained in an open position during the interval of time in machine operation when needles are moving upwardly relative to their associated revolving cylinder at each feeding unit into the region of the doffer roll to receive fiber therefrom, followed by movement of fiber-charged needles downwardly away from the doffer roll. Subsequently, the fiber charged needles are circumferentially moved into the region of a yarn charging or feeding station where the needles are charged with yarn and then caused to knit before being recycled in another machine knitting sequence. Typically, a plurality of yarn feeding stations are circumferentially spaced around a single needle cylinder.
Particularly in such knitting machines where the knitting of multi-color fabric patterns is involved, a plurality of fiber feeding stations may preceed each individual yarn feeding station. Experience has shown that such an operating sequence can result in the development of loose or stray fibers in and around the cylinder circumference.
Sufficient stray fiber can occur in regions about the top and upper outer side edge portions of the cylinder to cause a gradual build-up and collection of such stray fibrous material as slugs or fiber balls upon the leading or front edges of the respective individual latch guards. As the build up of such stray fibers upon the latch guard front end portions continues, eventually a point is reached where such a mass or wad or fiber breaks away from such forward end of the latch guard, is carried forwardly about the outer periphery of the cylinder, and becomes engaged with the needles (and sinkers) operating in a fiber feeding station or in a yarn feeding station. The consequence is that the freed fiber ball becomes captured by one or more needles, is knitted into the fabric being produced, so that a fault results.
In a multi-color pattern knitting operation, such a fault results in a noticeable or visible imperfection in the fabric pattern which is considered undesirable and unacceptable from the standpoint of producing a quality, commercially acceptable knitted fabric product.
Since there does not appear to be any convenient or practical way to eliminate the presence of a latch guard from the vicinity of a fiber feeding unit without causing a disastrous number of dropped stitches (caused by some needle latches being closed at the time when fiber is being loaded thereinto by a doffer roll), a considerable need has developed in this field for a means of reliably avoiding, and preferably substantially completely eliminating, the collection and subsequent release of fiber balls from the forward ends of latch guards.
So far as is now known, no one has heretofore succeeded in providing a practical means or technique for minimizing or eliminating such fiber ball production and release problem.